(1) Field of the Invention
The present invention relates generally to carotenoid-containing compositions, methods for inhibiting the growth of pathogenic bacteria, and methods for preventing or treating a bacterial infection in a subject via the administration of carotenoids.
(2) Description of the Related Art
Approximately two-thirds of the world's population is infected with Helicobacter pylori bacteria. Many people that are infected with the bacteria never suffer any symptoms related to the infection. In some cases, however, H. pylori infection can cause chronic active, chronic persistent, or atrophic gastritis. Infection with H. pylori also causes duodenal and gastric ulcers. In fact, H. pylori causes more than 90% of duodenal ulcers and 80% of gastric ulcers. The infection has additionally been associated with dyspepsia, iron-deficient anemia, and gastric malignancy. Further, approximately 15% of infected individuals will at some time develop peptic ulcer disease or gastric adenocarcinoma, which is the second most common cause of cancer deaths worldwide. Solnick, et al., Natural Acquisition of Helicobacter pylori Infection in Newborn Rhesus Macaques, J. Clin. Microbio. 41(12): 5511-5516 (2003).
Helicobacter pylori, which was previously known as Campylobacter pylori, is a gram-negative, spiral-shaped bacterium. It protects itself from the harsh acidic environment of the stomach by covering itself with the mucus of the stomach. Once covered, it is able to fight any stomach acid that does reach it with urease, an enzyme it possesses. Once nestled within the stomach mucus, H. pylori is able to penetrate the protective lining of the stomach, induce inflammatory cytokines, and cause gastric inflammation.
It is not currently known how H. pylori is transmitted or why some people become symptomatic while others do not. The bacteria are most likely spread from person to person through fecal-oral or oral-oral routes. Contaminated water or food sources may also contribute to the transmission of the bacteria.
The avoidance of H. pylori infection in infants and children is particularly important, as the incidence of H. pylori infection is greatest in childhood, particularly in developing countries where infection rates can be as high as 50% by age 5 years. Precise estimates of the age of acquisition of the invention are difficult to obtain because most children that are infected are asymptomatic. Even without symptoms, however, the infection can develop into more dangerous conditions such as antral gastritis, the most common manifestation in children. In addition, if an individual becomes infected with H. pylori during childhood, the infection may remain in his system throughout the course of his life, potentially leading to other diseases in adulthood.
Treatment for H. pylori infection currently consists of 10 days to 2 weeks of antibiotic treatment, such as with amoxicillin, tetracycline, metronidazole, or clarithromycin, plus either ranitidine bismuth citrate, bismuth subsalicylate, or a proton pump inhibitor. The disadvantage to widespread antibiotic treatment is the development of antibiotic resistance. The H. pylori infection has previously been shown to be resistant to several antibiotic treatments, contributing to treatment failure in a number of cases. F Mégraud, H pylori Antibiotic Resistance: Prevalence, Importance, and Advances in Testing, Gut 53: 1374-1384 (2004). In a particular study, 29% of the H. pylori strains tested were resistant to clarithromycin, 24% to metronidazole, and 10% were resistant to both clarithromycin and metronidazole. Kato, et al., Antibiotic Resistance of Helicobacter pylori Strains in Japanese Children, J. Clin. Microbio. 40(2): 649-653 (2002). Thus, infected individuals cannot be assured that antibiotic treatment will be effective.
Therefore, a need remains for a method for preventing or treating H. pylori infection in subjects. It would also be beneficial to provide a method for achieving such prevention or treatment through the use of compositions other than traditional antibiotics.